The past 25 years have seen considerable progress in the development of microfabricated systems for use in the chemical and biological sciences. Interest in microfluidic technology has driven by concomitant advances in the areas of genomics, proteomics, drug discovery, high-throughput screening and diagnostics, with a clearly defined need to perform rapid measurements on small sample volumes. At a basic level, microfluidic activities have been stimulated by the fact that physical processes can be more easily controlled when instrumental dimensions are reduced to the micron scale.1The relevance of such technology is significant and characterized by a range of features that accompany system miniaturization.

My lecture will discuss how the spontaneous formation of droplets in microfluidic systems can be exploited to perform a variety of complex analytical processesand why the marriage of such systems with optical spectroscopies provides a direct route to high-throughput and high-information content experimentation.

Droplet-based microfluidic systems allow the generation and manipulation of discrete droplets contained within an immiscible continuous phase.2They leverage immiscibility to create discrete volumes that reside and move within a continuous flow. Significantly, such segmented-flows allow for the production of monodisperse droplets at rates in excess of tens of KHz and independent control of each droplet in terms of size, position and chemical makeup. Moreover, the use of droplets in complex chemical and biological processing relies on the ability to perform a range of integrated, unit operations in high- throughput. Such operations include droplet generation, droplet merging/fusion, droplet sorting, droplet splitting, droplet dilution, droplet storage & droplet sampling.3-4I will provide examples of how droplet-based microfluidic systems can be used to perform a range of experiments including nanomaterial synthesis,5cell-based assays6and DNA amplification.

The considerable advantages that are afforded through the use of microfluidic systems are in large part made possible by system downscaling and the associated improvements in mass and thermal transfer. Nonetheless, handling and processing fluids with instantaneous volumes on the fL-nL scale represents a critical challenge for molecular detection, and still defines one of the key limitations in the use of a microfluidic system in a given application. To this end, I will also describe recent studies focused on the development of novel imaging flow cytometry platform that leverages the integration of inertial microfluidics with stroboscopic illumination8to allow for high-resolution imaging of cells at throughputs approaching 105cells/second.